A read-only instance is a read-only copy of your primary instance. It routes queries away from the primary instance, letting you scale read capacity beyond the limits of a single instance. Starting June 20, 2024, ApsaraDB RDS for MySQL supports read-only instances on RDS Basic Edition.
RDS Basic Edition uses a single-node architecture where computing is decoupled from storage. No secondary instance serves as a hot standby. If the primary instance fails, restarts, changes specifications, or upgrades the database engine version, the service may be unavailable for an extended period. If your workload requires high availability, use RDS High-availability Edition instead. For details, see RDS Basic Edition and RDS High-availability Edition.
Availability
June 20, 2024
Supported engine versions
Read-only instances on RDS Basic Edition support primary instances that run MySQL 5.7 or MySQL 8.0.
Billing
Both subscription and pay-as-you-go billing methods are supported.
Use cases
| Scenario | How read-only instances help |
|---|---|
| Read-heavy workloads | Route read queries to one or more read-only instances to offload the primary instance. |
| Primary instance temporarily unavailable | Serve read requests through a read-only instance during backup windows or maintenance operations. |
| Report and analytics workloads | Run large analytical queries on a read-only instance without affecting primary instance performance. |
| Read/write splitting | Pair read-only instances with the read/write splitting feature to prevent lock contention and improve throughput. |
Supported specifications
The following specifications are available for RDS Basic Edition read-only instances. All instance types belong to the general-purpose instance family and use the standard (x86) architecture.
| RDS edition | Instance family | Instance type | CPU cores and memory | Maximum connections | Maximum I/O bandwidth (Mbit/s) | Storage capacity |
|---|---|---|---|---|---|---|
| RDS Basic Edition | General-purpose | mysqlro.n2.small.c | 1 core, 2 GB | 2,000 | 1,024 |
|
| mysqlro.n2.medium.c | 2 cores, 4 GB | 4,000 | 1,024 | |||
| mysqlro.n4.medium.c | 2 cores, 8 GB | 6,000 | 1,024 | |||
| mysqlro.n8.medium.c | 2 cores, 16 GB | 8,000 | 1,024 | |||
| mysqlro.n2.large.c | 4 cores, 8 GB | 6,000 | 1,536 | |||
| mysqlro.n4.large.c | 4 cores, 16 GB | 8,000 | 1,536 | |||
| mysqlro.n8.large.c | 4 cores, 32 GB | 12,000 | 1,536 | |||
| mysqlro.n2.xlarge.c | 8 cores, 16 GB | 8,000 | 2,048 | |||
| mysqlro.n4.xlarge.c | 8 cores, 32 GB | 10,000 | 2,048 | |||
| mysqlro.n8.xlarge.c | 8 cores, 64 GB | 16,000 | 2,048 |
Storage options are explicitly listed for mysqlro.n2.small.c. For other instance types, refer to the ApsaraDB RDS console for available storage options.
Purchase a read-only instance
Log on to the ApsaraDB RDS console. In the top navigation bar, select the region where the primary instance resides. Find the instance and click its ID.
On the Basic Information page, locate the Instance Distribution section and click Add to the right of Read-only Instance.
On the Read-only Instance buy page, set Edition to Basic Edition and configure the remaining parameters. For a full parameter reference, see Create a read-only ApsaraDB RDS for MySQL instance.